Glow plug for internal combustion engines



New, 5, 1935. A, wlDMANN 2,019,836 I GLOW PLUG FOR INTERNAL COMBUSTIQN ENGINES Filed Jan. 14, 1951 fZEl fiDULFH MUMHNM Patented Nov. 5, 1935 UNITED STATES PATENT ()FFIQE GLOW PLUG FOR INTERNAL COMBUSTION ENGINES Application January 14, 1931, Serial No. 508,709

Claims.

This invention relates to internal combustion engines and more particularly to glow plugs.

An object of the invention is to provide a novel and improved glow plug for compression- 5 ignition engines which will withstand many hours of use and engine operation.

Another object of the invention is to provide a glow plug in which the resistance wire is attached to the electrode so that it will withstand many hours of use and exposure in the combustion chamber of a Diesel engine without breaking or becoming loose.

A further object of my invention is to provide a glow plug in which the resistance wire is secured to the electrode so that a large area of the contacting surfaces will remain in an intimate relation for a long number of engine operatinghours without oxidizing or breaking.

A further object of the invention resides in the method of securing an incandescent wire to an electrode so that the engaging surfaces will remain in an intimate contacting relation for a relatively long period of use with a high speed Diesel type of engine.

5 Other objects of the invention will appear from the following description taken in connection with the drawing, which forms a part of this specification, and in which:

Fig. i is an elevaticnal view of a glow plug con- 0 structed in accordance with my invention;

Fig. 2 is a fragmentary view of the same with the body and resistance wire in section;

Fig. 3 is a sectional view taken on line 33 of Fig. 2 and showing the application of the sealing tool;

Fig. 4 is a sectional view taken on line 4-4 of Fig. 3 with the tool shown in dotted lines.

Referring now to the drawing by characters of reference, it indicates the body of the glow plug formed with an exterior threaded portion H at one end which is adapted to be screwed into an opening in the wall of an engine cylinder. Extending through the body is an electrode l2 which is separated from the body by means of the shell [3 formed of insulating material. The exterior end of the electrode is provided with a groove I4 for the reception of a wire (not shown) connected with a source of electrical supply. A high resist ance wire 15 is secured to the inner end of the electrode projecting beyond the body and also to the inner end of the bodyso that when energized, it will produce heat within the combustion chamber of a Diesel or other type of engine. One end of the wire extends into an opening l6 formed in the body and is securely retained therein by the wedge member I! which is driven into an opening extending transversely of the body. The wire is coiled tightly around the electrode and is anchored in a recess i 8 therein, and is also coiled to provide larger convolutions which are spaced from the electrode. By tightly winding the wire around the electrode and in the recess I8, a rigid support is provided for the end of the wire which is fixed to the electrode.

The electrode is usually formed of a high heat 10 resisting type of metal, such as steel. The resistance wire I 5 is usually constructed of a metal having a high electrical resistance and of a character such that it will withstand the heat and vibration to which it may be subjected when in 15 for this purpose is an alloy composed mainly of nickel and chromium.

Considerable difiiculty has been encountered in 20 securely fixing the resistance wire to the electrode of glow plugs so that the wire will not break and the contacting surfaces maintain their intimate relation after a few operating hours when associated with an engine of the Diesel type running 25 at a relatively high R. P. M. It has heretofore been proposed to employ wedges or plugs as a means of securely fastening resistance wire to the electrode, and welding the resistance Wire to the electrode has also been tried, but both of these 3{) methods and other similar methods of fastening fail to provide a connection which will answer the operating time requirements of commercial use. With such methods of fastening the wire to the electrode, engine vibration, the explosion 5 shocks and the intense heat developed in the combustion chamber soon cause separation of the connection so: that oxidization of the contact surfaces takes place or the wire breaks before the glow plug has been in use more than a very few 40 hours. Securing by means of welding requires heat of a character which leaves the wire and electrode brittle so that they are quickly broken by engine vibration.

In order to overcome the present objections to 45 the manner of fastening the resistance wire to the electrode, I provide a securing means which will tightly seal a considerable length of the wire within the electrode and I have found that the life of this contact connection lasts many oper- 50 ating hours of the engine with which it is associated and without any shield. I provide the electrode with a transversely extending hole [9 which is offset from the center of the electrode, and through this hole I press the end of the re- 55 sistance wire which is to be secured to form a. contact with the electrode. After forcing the end of the wire through the hole, pressure is exerted by a special tool 20 against the surface of the electrode lengthwise of the wire projecting through the electrode and in a circular direction around such end of the wire. A force is applied to the tool so that the metal sm'rounding the length of wire in the hole is compressed around the wire the length of the tool, as indicated at 2| in Figs. 3 and 4, and will thus seal the contacting surfaces circularly along such length. Due to the offset relation of the hole, the metal of the electrode on one side or" the wire is comparatively thin and will be more readily compressed to form the seal. This manner of pressing the electrode around the contact end of the wire extending therethrough will prevent air or gases from Working along the wire from either end and will tightly secure the wire. Vibration will not readily cause separation of such a seal.

Although the invention has been described in connection with a specific embodiment, the principles involved are susceptible of numerous other applications which will readily occur to persons skilled in the art. The invention is therefore to be limited only as indicated by the scope of the appended claims.

What I claim is:

1. A glow plug comprising a body, an electrode extending through the body, said electrode having an aperture of appreciable length extending therethrough, and a resistance wire extending through the aperture in the electrode and secured to the body, said wire having appreciable surface contact with the wall of the aperture, said electrode being compressed around the length of wire in the aperture to form a sealed contact connection.

2. A glow plug comprising a body, an electrode extending through the body, said electrode having an aperture extending transversely therethrough, and a resistance wire having one end extending into the aperture in the electrode and the other end fixed to the body, said electrode being compressed around the wire end in the aperture substantially the length thereof.

3. A glow plug comprising a body, an electrode extending through the body, said electrode having an aperture extending transversely thereof and in an ofi-center relation, and a resistance wire projecting into the electrode aperture and secured to the body, the surface of the electrode over the aperture being pressed inwardly circularly across and lengthwise of the wire therein.

4. The method of securing a resistance wire to the electrode of a glow plug comprising forming an aperture transversely in the electrode and offset relative to the center, pressing an end of the wire into the aperture, and applying pressure against the surface of the electrode to compress the electrode circularly around and substantially the length of the inserted end of the 5. A glow plug comprising a body, an electrode insulated therefrom, said electrode having an opening therein, and a resistance wire having one end extending into the opening and the other end secured to the body, the metal of the electrode around the wire in the opening being compressed so that there is a sealed contact between an appreciable length of the resistance wire and the electrode.

ADOLPH WIDMANN. 

